Display device

ABSTRACT

A display device includes a controller that determines the mode of inclination of a display object that is an image shaped to point to one direction, and a drawing unit that projects light representing the display object in the mode of inclination determined by the controller onto a windshield to cause the light to be reflected off the windshield toward a user in the vehicle to enable the user to visually recognize the display object in the mode of inclination as a virtual image through the windshield. The controller determines the mode of inclination of the display object that points to the one direction as a navigation direction, by controlling yaw and roll angles of the display object depending on the attribute of a path point that is set on the path to navigate the vehicle to a destination.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of PCT International Application No.PCT/JP2021/031521 filed on Aug. 27, 2021, designating the United Statesof America, which is based on and claims priority of Japanese PatentApplication No. 2020-146228 filed on Aug. 31, 2020.

FIELD

The present disclosure relates to a display device for enabling a userto visually recognize an image as a virtual image.

BACKGROUND

Display devices have conventionally been proposed in which lightrepresenting an image is projected onto and reflected off a translucentplate-like display medium while showing a background through the displaymedium to a user so as to enable the user to visually recognize theimage as a virtual image. Such display devices use so-called augmentedreality (AR) and are capable of displaying, in a real background, animage related to the background. In particular, in fields such asautomobile-related fields, so-called head-up displays (HUDs) have beendeveloped that display an image indicating speed or various types ofwarnings as a virtual image in front of a windshield during driving(see, for example, Patent Literature (PTL) 1).

The use of such a display device enables a driver as the user to seedriving-related images (e.g., a map, a speed meter, or a navigationdirection), i.e., display objects, without large eye movements whileseeing the outside world ahead. The driver is thus able to drive morecarefully.

CITATION LIST Patent Literature

PTL 1: International Publication No. 2015/118859

SUMMARY

However, the display device which is the head-up display of the abovePTL 1 can be improved upon.

In view of this, the present disclosure provides a display devicecapable of improving upon the above related art.

A display device according to one aspect of the present disclosureincludes a control circuit that determines a mode of inclination of adisplay object that is an image shaped to point to one direction; and aprojector that projects light representing the display object in themode of inclination determined by the control circuit onto a displaymedium provided in a vehicle, to cause the light to be reflected off thedisplay medium toward a user in the vehicle to enable the user tovisually recognize the display object in the mode of inclination as avirtual image through the display medium. The control circuit determinesthe mode of inclination of the display object that points to the onedirection as a navigation direction, by controlling a yaw angle and aroll angle of the display object in accordance with an attribute of apath point that is set on a path for navigation of the vehicle to adestination.

Note that these general and specific aspects may be achieved by asystem, a method, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or may be achievedby any combination of a system, a method, an integrated circuit, acomputer program, and a computer-readable recording medium. Therecording medium as referred to herein may be a non-transitory recordingmedium.

The display device according to one aspect of the present disclosure iscapable of improving upon the above related art.

Further advantages and effects of one aspect of the present disclosurebecome apparent from the specification and the drawings. Theseadvantages and/or effects are each implemented by features described insome embodiments and in the specification and drawings, but not all ofthem have to be implemented necessarily in order to achieve one or moreof the same features.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing an example of use of a display deviceaccording to an embodiment.

FIG. 2 is a diagram showing one example of the interior of a vehiclethat includes the display device according to the embodiment.

FIG. 3 is a block diagram illustrating a functional configuration of thedisplay device according to the embodiment.

FIG. 4 is a diagram showing one example of a display object according tothe embodiment.

FIG. 5 is a diagram showing a specific example of a display objectoverlaid on a road surface by the display device according to theembodiment.

FIG. 6 is a diagram showing another specific example of a display objectoverlaid on a road surface by the display device according to theembodiment.

FIG. 7 is a diagram showing an example of comparison between aconventional display object and a display object overlaid on a roadsurface by the display device according to the embodiment.

FIG. 8 is a diagram showing another example of comparison between aconventional display object and a display object overlaid on a roadsurface by the display device according to the embodiment.

FIG. 9A is a diagram showing one example of controlling the yaw angle ofa display object according to the embodiment.

FIG. 9B is a diagram showing one example of a method of determining apath point according to the embodiment.

FIG. 10 is a diagram showing one example of controlling the roll angleof a display object according to the embodiment.

FIG. 11 is a diagram showing one example of controlling the position ofa display object according to the embodiment.

FIG. 12 is a diagram showing one example of controlling the shape of adisplay object according to the embodiment.

FIG. 13 is a diagram showing one example of controlling the design of adisplay object according to the embodiment.

FIG. 14 is a diagram showing another example of controlling the designof a display object according to the embodiment.

FIG. 15 is a diagram showing one example of controlling the movement ofa display object according to the embodiment.

FIG. 16 is a diagram showing one example of controlling the height of adisplay object according to the embodiment.

FIG. 17 is a diagram showing a more specific example of controlling theheight of a display object according to the embodiment.

FIG. 18 is a diagram showing another example of controlling the heightof a display object according to the embodiment.

FIG. 19 is a diagram showing one example of controlling an offset in theyaw angle of a display object according to the embodiment.

FIG. 20 is a flowchart showing processing operations of the displaydevice according to the embodiment.

DESCRIPTION OF EMBODIMENT (Underlying Knowledge Forming Basis of thePresent Disclosure)

The inventors of the present disclosure have found the followingpossible problems with the display device according to PTL 1 describedin the “Background Art”.

The display device according to PTL 1 displays guidance for vehiclenavigation. That is, the display device overlays a display object suchas an arrow on a road surface. The displayed guidance is expressed asAR, and the display object displayed as guidance may have, for example,a long carpet-like shape.

The display object displayed as guidance may, however, extend off adriving lane when navigation uses a low-precision map or a sensor withlow detection accuracy. In other words, overlay misregistration mayoccur. There is also a possibility that the long display object as awhole may not fit in a display range and may be lost in part. Suchoverlay misregistration and loss are likely to give a feeling ofdiscomfort to a user. Besides, the feeling of discomfort may mislead theuser or the vehicle.

To solve the problems described above, a display device according to oneaspect of the present disclosure includes a controller that determines amode of inclination of a display object that is an image shaped to pointto one direction; and a drawing unit that projects light representingthe display object in the mode of inclination determined by thecontroller onto a display medium provided in a vehicle, to cause thelight to be reflected off the display medium toward a user in thevehicle to enable the user to visually recognize the display object inthe mode of inclination as a virtual image through the display medium.The controller determines the mode of inclination of the display objectthat points to the one direction as a navigation direction, bycontrolling a yaw angle and a roll angle of the display object inaccordance with an attribute of a path point that is set on a path fornavigation of the vehicle to a destination. Please note that thecontroller may be configured as a control circuit, and the drawing unitmay be configured as a projector.

Since the yaw and roll angles of the display object are controlled inaccordance with the attribute of the path point, it is possible todisplay the display object like a bird or plane view to lead the vehicleto the destination. This allows the display object to be formed not intoa long carpet-like shape but into a short shape such as an arrowheadpointing to one direction. As a result, it is possible to reduce theoccurrence of overlay misregistration or loss of the display object andalleviate user discomfort caused by the overlay misregistration or lossof the display object while appropriately notifying the user of thenavigation direction by the one direction pointed to by the displayobject.

The controller may further control a lateral position of the displayobject visually recognized in accordance with a direction from thevehicle to the path point, the lateral position being a position in abreadth direction of the vehicle.

This reduces the occurrence of overlay misregistration. The lateralposition of the display object is also controlled, for example, suchthat the direction from the vehicle to the display object is orientedcloser to the travel direction of the vehicle than to the direction fromthe vehicle to the path point. The control reduces the possibility that,even if the display object is displayed within a predetermined range inthe lateral position, the display object sticks to the boundary of thisrange or suddenly moves off this boundary.

The controller may control the lateral position of the display object toallow the display object to be visually recognized within apredetermined range in the breadth direction of the vehicle.

This reduces the possibility that the display object becomes lost orinvisible.

The controller further may control a position of the path point inaccordance with a travelling speed of the vehicle.

Accordingly, the display object can provide the user with an appropriatenavigation direction depending on the travelling speed. For example, inthe case where the travelling speed of the vehicle is high, the displayobject points to a direction to a far path point as the navigationdirection. This enables the user who makes a right or left turn at agiven intersection to have sufficient lead time to prepare for the rightor left turn. In the case where the travelling speed of the vehicle islow, the display object points to a direction to a path point close tothe vehicle as the navigation direction. This prevents the displayobject from pointing to a right or left turn direction when there isanother intersection immediately before a target intersection.

When controlling the position of the path point, the controller maydetermine a first point on the path depending on the travelling speed ofthe vehicle, when there is a variable section between a current locationof the vehicle and the first point and when a difference between atravel direction of the vehicle and a path direction at a second pointlocated immediately before the variable section is outside apredetermined range, the variable section being a section in which anabsolute value for a rate of change in the path direction at each pointon the path is greater than a threshold value, may determine the secondpoint as the position of the path point; and when the difference fallswithin the predetermined range, may determine the first point as theposition of the path point.

In the case where there is a variable section, either one of the firstpoint and the second point located before and after the variable sectionis determined as the position of the path point, depending on the traveldirection of the vehicle. This reduces the possibility that the displayobject points to an inappropriate navigation direction as the traveldirection of the vehicle.

The controller may further control a depth position of the displayobject visually recognized in accordance with a travelling speed of thevehicle, the depth position being a position in a travel direction ofthe vehicle.

This reduces the occurrence of overlay misregistration. Moreover, as thetravelling speed of the vehicle becomes higher, a position farther fromthe vehicle is determined as the depth position, and as the travellingspeed of the vehicle becomes lower, a position closer to the vehicle isdetermined as the depth position. This avoids the display object frombeing overlaid on a vehicle travelling ahead, for example when thevehicle is travelling slowly on a relatively congested road. The user asa driver tends to focus on a far point when the travelling speed of thevehicle is high, and tends to focus on a near point when the travellingspeed of the vehicle is low. This reduces user's eye movements to seethe display object and allows the user to drive carefully.

The controller may limit the depth position of the display object toallow the display object to be visually recognized within apredetermined range in an up-down direction of the vehicle.

This reduces the possibility that the display object becomes lost orinvisible.

The display device may further include a first input unit that acquiresreliability information indicating reliability of the navigation. Thecontroller may control either a height of the display object visuallyrecognized from a road surface or a dynamic design of the display objectin accordance with the reliability information acquired by the firstinput unit.

For example, in the case where the reliability of the navigation is low,overlay misregistration may occur in the display object, or the onedirection pointed to by the display object may be shifted from anappropriate navigation direction. However, the display device accordingto one aspect of the present disclosure controls the height or dynamicdesign of the display object when the reliability of the navigation islow. As one specific example, the display object may be displayed atapparently a high position, or the display object may blink on and off.This alleviates user discomfort caused by overlay misregistration or theaforementioned shift in the one direction.

The controller may further control a height of the display objectvisually recognized from a road surface in accordance with a distancefrom a current location of the vehicle to a right/left turn point on thepath.

Accordingly, it is possible to appropriately notify the user of theright/left turn point. Besides, in the case where the height of thedisplay object is controlled to move the display object from a highposition to a low position as the vehicle approaches the right/left turnpoint, it is possible to prompt the user to slow down the vehicle. Thatis, it is possible to prompt the user to drive carefully.

The attribute of the path point may be a tangential direction at thepath point on the path, and when determining the mode of inclination ofthe display object, the controller may control the yaw angle of thedisplay object to cause the one direction to coincide with thetangential direction. Alternatively, the attribute of the path point maybe a position of the path point, and when determining the mode ofinclination of the display object, the controller may control the yawangle of the display object to cause the one direction coincide with adirection from the vehicle to the path point.

Accordingly, the one direction pointed to by the display object isoriented in the tangential direction or in the direction from thevehicle toward the path point. Therefore, it is possible to notify theuser of an appropriate navigation direction for directing the vehicle tothe path point by the one direction pointed to by the display object.

The controller may further apply an offset to the yaw angle and the rollangle of the display object when a traffic lane different from a drivinglane of the vehicle is recommended as a recommended traffic lane in thenavigation.

Accordingly, in the case where the one direction pointed to by thedisplay object is oriented to the recommended traffic lane as a resultof the application of an offset, it is possible to prompt the user todrive on the recommended traffic lane.

The controller may further change a shape of the display object inaccordance with the yaw angle of the display object.

Accordingly, even if the depth position of the display object is farfrom the vehicle, the visibility of the display object can be improvedby changing the shape of the display object.

When determining the mode of inclination of the display object, thecontroller may further control a pitch angle of the display object inaccordance with the yaw angle of the display object.

Accordingly, even if the depth position of the display object is farfrom the vehicle, the visibility of the display object can be improvedby controlling the pitch angle of the display object.

The controller may further control a design of the display object inaccordance with a distance from a current location of the vehicle to aright/let turn point located ahead of the path point on the path.Alternatively, the controller may further control a design of thedisplay object in accordance with an expected arrival time from acurrent location of the vehicle to a right/left turn point located aheadof the path point on the path.

Accordingly, it is possible to notify the user of the navigationdirection to the right/left turn point by the mode of inclination of thedisplay object and to appropriately notify the user of the timing of aright or left turn at the right/left turn point by controlling thedesign of the display object. That is, even if the navigation directionto the right/left turn point is different from the right or left turndirection at the right/left turn point, it is possible to appropriatelynotify the user of both the navigation direction and the right or leftturn direction at the same time.

The controller may further move the display object in the navigationdirection when a distance from a current location of the vehicle to aright/left turn point on the path is less than or equal to a thresholdvalue. Alternatively, the controller may further move the display objectin the navigation direction when an expected arrival time from a currentlocation of the vehicle to a right/left turn point on the path is lessthan or equal to a threshold value.

This allows the user to more easily notice the right/left turn point andto know the timing of a right or left turn at the right/left turn point.

The display device may further include a second input unit that acquiressensing information indicating an approach of another vehicle from asensor that detects the approach of the other vehicle to the vehicle.The controller may further control a design of the display object inaccordance with the sensing information acquired by the second inputunit.

Accordingly, the attention of the user can be attracted to the approachof other vehicles by controlling the design of the display object. Forexample, in the case where the vehicle changes its traffic lane, it ispossible to attract the attention of the user to the approach of othervehicles.

These general and specific aspects may be realized by a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or may be realizedby any combination of a system, a method, an integrated circuit, acomputer program, or a computer-readable recording medium. Moreover, therecording medium as referred to herein may be a non-transitory recordingmedium.

Hereinafter, one embodiment will be described in detail with referenceto the drawings.

The embodiment described below illustrates one generic or specificexample of the present disclosure. Numerical values, shapes, materials,constituent elements, the arrangement and positions of constituentelements, the form of connection of constituent elements, steps, asequence of steps, and so on in the following embodiment are merely oneexample, and do not intend to limit the scope of the present disclosure.Among the constituent elements in the following embodiment, those thatare not recited in any one of the independent claims which define thegeneric concept of the present disclosure are described as arbitraryconstituent elements.

Note that each drawing is a schematic diagram and does not necessarilyprovide precise depiction. Substantially the same constituent elementsare given the same reference signs throughout the drawings, and theirdetailed description is omitted or simplified.

Embodiment [Overall Configuration]

FIG. 1 is a diagram showing an example of use of a display deviceaccording to an embodiment of the present disclosure.

Display device 100 according to the present embodiment is configured asa head-up display (HUD) and mounted on vehicle 2. As one specificexample, display device 100 may be built in dashboard 2 b of vehicle 2.

Display device 100 projects video image light representing displayobject 10 onto windshield 2 a of vehicle 2. As a result, the video imagelight is reflected off windshield 2 a and transmitted to, for example,user 1 who is the driver of vehicle 2. Accordingly, user 1 visuallyrecognizes display object 10 as a virtual image through windshield 2 a.That is, display device 100 allows user 1 to visually recognize displayobject 10 as a virtual image. Note that allowing user 1 to visuallyrecognize display object 10 as a virtual image in this way ishereinafter also referred to as displaying display object 10, and theoperation of projecting the video image light representing the displayobject is synonymous with the operation of displaying display object 10.Windshield 2 a is one example of a display medium. In the presentembodiment, the display medium is windshield 2 a, but when vehicle 2includes a combiner, display device 100 may project video image lightonto the combiner that serves as the display medium.

Windshield 2 a is a translucent plate-like display medium. Thus, displaydevice 100 allows user 1 to visually recognize display object 10 as avirtual image while showing a background such as a road surface throughwindshield 2 a to user 1. That is, AR achieves display of display object10 in a real background.

Display object 10 is an image shaped to point to one direction. As onespecific example, display object 10 is a three-dimensional image like anarrowhead. Note that the one direction is the direction of the tip endof the arrowhead and hereinafter also referred to as a pointeddirection. The pointed direction of display object 10 is oriented to thedirection of guiding vehicle 2 to a destination, i.e., a navigationdirection.

Therefore, the use of display device 100 allows a driver as user 1 tosee display object 10 while seeing the outside world ahead and withoutlarge eye movements. Thus, the driver is able to drive more carefullywhile grasping the navigation direction.

FIG. 2 is a diagram showing one example of the interior of vehicle 2that includes display device 100 according to the present embodiment.

Display device 100 that is put in dashboard 2 b out of sight projectsvideo image light onto windshield 2 a. For example, as a result of theprojection of the video image light by display device 100, displayobject 10 appears as a virtual image within display range d1 ofwindshield 2 a.

FIG. 3 is a block diagram illustrating a functional configuration ofdisplay device 100 according to the present embodiment.

Display device 100 includes input unit 110, controller 120, and drawingunit 130.

Input unit 110 acquires vehicle-related information from each ofnavigation device 21, vehicle control device 22, and sensor 23, all ofwhich are mounted on vehicle 2.

Navigation device 21 is a device for navigating vehicle 2 to adestination, using a satellite positioning system such as a globalpositioning system (GPS). Navigation device 21 outputs vehicle positioninformation that indicates the current location of vehicle 2, pathinformation that indicates the path from the current location of vehicle2 to the destination, and vehicle azimuth information that indicates thetravel direction of vehicle 2 as the aforementioned vehicle-relatedinformation.

Vehicle control device 22 may be configured as, for example, anelectronic control unit (ECU) mounted on vehicle 2 and output vehiclespeed information that indicates the travelling speed of vehicle 2 asthe aforementioned vehicle-related information.

Sensor 23 detects objects such as people or other vehicles aroundvehicle 2 and outputs sensing information that indicates the result ofthe detection as the aforementioned vehicle-related information. Forexample, sensor 23 may detect objects such as people or other vehiclesby light detection and ranging (LiDAR).

Controller 120 determines a display form of display object 10, using thevehicle-related information acquired by input unit 110. Specifically,controller 120 includes position processor 121, inclination processor122, design processor 123, shape processor 124, and path-pointdeterminer 125.

Path-point determiner 125 determines a path point on the path indicatedby the aforementioned path information and notifies position processor121 and inclination processor 122 of the determined path point.

Position processor 121 determines the position of display object 10visually recognized by user 1, using the path point determined bypath-point determiner 125. This position is a position in athree-dimensional space and includes a lateral position in the breadthdirection of vehicle 2, a depth position in the travel direction ofvehicle 2, and a height from the road surface.

Inclination processor 122 determines the mode of inclination of displayobject 10, using the path point determined by path-point determiner 125.The mode of inclination is determined by the yaw, roll, and pitch anglesof display object 10.

Design processor 123 determines the design of display object 10. Notethat the design of display object 10 according to the present embodimentrefers to coloration or brightness of display object 10 and includes adynamic change in coloration or brightness.

Shape processor 124 determines the shape of display object 10. Note thatthe shape of display object 10 according to the present embodiment isdefined by the overall length or width of display object 10. The overalllength refers to the length of display object 10 in the pointeddirection indicated by display object 10, and the width refers to thelength of display object 10 in the direction perpendicular to thepointed direction. Shape processor 124 determines the shape of displayobject 10 by changing the ratio between the overall length and thewidth.

Controller 120 outputs display-form information that indicates the formof display including the aforementioned position, the aforementionedmode of inclination, the aforementioned design, and the aforementionedshape to drawing unit 130.

Drawing unit 130 acquires the display-form information from controller120 and draws display object 10 in accordance with the display-forminformation. For example, drawing unit 130 may include a light sourceand an optical system and generate video image light representingdisplay object 10 in the form of display indicated by the display-forminformation so as to allow user 1 to visually recognize display object10 in the form of display. Then, drawing unit 130 projects the videoimage light onto windshield 2 a. As a result, object 10 with thedetermined mode of inclination, the determined design, and thedetermined shape is visually recognized at the determined position byuser 1. That is, as to the mode of inclination, drawing unit 130projects the video image light representing display object 10 in themode of inclination determined by inclination processor 122 ofcontroller 120 onto windshield 2 a mounted on vehicle 2 so as to causethe video image light to be reflected off windshield 2 a toward user 1in vehicle 2 and to allow user 1 to visually recognize display object 10in the mode of inclination as a virtual image through windshield 2 a.

FIG. 4 is a diagram showing one example of display object 10 accordingto the present embodiment. Note that (a) in FIG. 4 shows the top view ofdisplay object 10, (b) in FIG. 4 shows the perspective view of displayobject 10, and (c) in FIG. 4 shows the position of display object 10 inthe travel direction of vehicle 2 and in the height direction.

As illustrated in (a) and (b) in FIG. 4 , display object 10 is formedinto a flat plate-like and approximately V or inverted V shape.Inclination processor 122 of controller 120 determines the mode ofinclination of display object 10 by controlling yaw angle ψ, roll angleφ, and pitch angle θ of display object 10.

Yaw angle ψ is the angle of rotation of display object 10 about a yawaxis extending in the thickness direction of display object 10 as acentral axis. For example, in the case where the pointed direction ofdisplay object 10 coincides with the travel direction of vehicle 2, yawangle ψ of display object 10 is 0°.

Roll angle φ is the angle of rotation of display object 10 about a rollaxis extending in the pointed direction of display object 10 as acentral axis. For example, in the case where display object 10 isarranged along a horizontal plane, roll angle φ of display object 10 is0°.

Pitch angle θ is the angle of rotation of display object 10 about apitch axis extending in a direction perpendicular to the yaw axis andthe roll shaft as a central axis. For example, in the case where displayobject 10 is arranged along a horizontal plane, pitch angle θ of displayobject 10 is 0°.

As illustrated in (c) in FIG. 4 , position processor 121 of controller120 determines position y of display object 10 in the travel directionof vehicle 2 on the basis of, for example, the vehicle speedinformation. Position y is indicated as the distance from vehicle 2 inthe travel direction. Position processor 121 further determines positionz as the height of display object 10. Position z is indicated as theheight from the road surface on which vehicle 2 is travelling.

[Display Example of Display Object]

FIG. 5 is a diagram showing a specific example of display object 10overlaid on a road surface by display device 100 according to thepresent embodiment.

For example, when vehicle 2 is approaching a T-junction, display device100 determines the mode of inclination of display object 10 such thatthe pointed direction of display object 10 coincides with the navigationdirection of vehicle 2. Then, display device 100 projects video imagelight representing display object 10 in the determined mode ofinclination onto windshield 2 a so as to allow user 1 to visuallyrecognize display object 10.

In the example illustrated in FIG. 5 , inclination processor 122 ofcontroller 120 determines a rightward navigation direction on the basisof the aforementioned information including the vehicle positioninformation, the path information, and the vehicle azimuth information.Then, inclination processor 122 sets yaw angle ψ of display object 10at, for example, −90° so that the pointed direction of display object 10coincides with the navigation direction. Inclination processor 122further sets roll angle φ of display object 10 at, for example, 90°according to yaw angle ψ.

Such display object 10 is overlaid and displayed on the road surface ofthe T-junction in order to appear as a virtual image through windshield2 a.

FIG. 6 is a diagram showing another specific example of display object10 overlaid on a road surface by display device 100 according to thepresent embodiment.

Even in the case where vehicle 2 is travelling on a road other than anintersection such as a T-junction, display device 100 determines themode of inclination of display object 10 such that the pointed directionof display object 10 coincides with the navigation direction of vehicle2 as illustrated in FIG. 6 . Then, display device 100 overlays anddisplays display object 10 in the determined mode of inclination on theroad surface.

FIG. 7 is a diagram showing an example of comparison between aconventional display object and display object 10 overlaid on a roadsurface by display device 100 according to the present embodiment.Specifically, (a) in FIG. 7 shows one example of a display objectoverlaid on the road surface by a conventional display device, and (b)in FIG. 7 shows one example of display object 10 overlaid on the roadsurface by display device 100.

As illustrated in (a) in FIG. 7 , the conventional display devicedisplays long carpet-like display object 90 overlaid on the roadsurface. The longitudinal direction of display object 90 coincides withthe navigation direction. In other words, display object 90 is arrangedalong the path to a destination. Here, the navigation direction or thepath may include errors if the navigation device uses a low-precisionmap or low-precision positioning. As a result, long display object 90may deviate from the road surface as illustrated in (a) in FIG. 7 . Thatis, overlay misregistration is likely to occur. Accordingly, displayobject 90 may hold the possibility of misleading the user and thepossibility of causing user discomfort.

On the other hand, display device 100 according to the presentembodiment displays arrowhead-shaped display object 10 overlaid on theroad surface as illustrated in (b) in FIG. 7 . Thus, even if thenavigation direction or the path includes errors, it is possible toavoid misleading user 1 and to alleviate discomfort felt by user 1

FIG. 8 is a diagram showing another example of comparison between aconventional display object and display object 10 overlaid on a roadsurface by display device 100 according to the present embodiment.Specifically, (a) in FIG. 8 shows another example of the display objectoverlaid on the road surface by a conventional display device, and (b)in FIG. 8 shows another example of display object 10 overlaid on theroad surface by display device 100.

As illustrated in (a) in FIG. 8 , the conventional display devicedisplays long carpet-like display object 90 overlaid on the roadsurface. Such display object 90 is displayed only within display range91. Thus, in the case where part of display object 90 extends offdisplay range 91 as illustrated in (a) in FIG. 8 , that part is notdisplayed and display object 90 that is lost in part is displayed withindisplay range 91. As a result, display object 90 may hold thepossibility of misleading the user and the possibility of causing userdiscomfort.

On the other hand, display device 100 according to the presentembodiment displays arrowhead-shaped display object 10 overlaid on theroad surface as illustrated in (b) in FIG. 8 . Accordingly, displayobject 10 is easily contained in display range d1, and the possibilityof losing part of display object 10 is reduced. As a result, displayobject 10 can avoid misleading user 1 and alleviate discomfort felt byuser 1.

[Yaw and Roll Angle Control of Display Object]

FIG. 9A is a diagram showing one example of controlling the yaw angle ofdisplay object 10 according to the present embodiment. Note that (a) inFIG. 9A shows one example of controlling yaw angle ψ, and (b) in FIG. 9Ashows another example of controlling yaw angle ψ, different from theexample illustrated in (a) in FIG. 9A.

First, path-point determiner 125 of controller 120 determines a pathpoint. This path point is a point that is set on the path to navigatevehicle 2 to a destination. Path-point determiner 125 controls theposition of the path point on the path indicated by the aforementionedpath information, depending on the travelling speed of vehicle 2. Aspecific method of determining the position of the path point will bedescribed later with reference to FIG. 9B.

In this determination of the path point, path-point determiner 125 maydetermine the path point nonlinearly relative to the travelling speed,or may determine the path point linearly relative to the travellingspeed. In the case where the travelling speed of vehicle 2 is used inthe control of display object 10, each constituent element included incontroller 120, such as path-point determiner 125, may use thetravelling speed indicated by the aforementioned vehicle speedinformation as the travelling speed of vehicle 2, and in the case wherethe distance from vehicle 2 is measured, each constituent element mayuse the current location of vehicle 2 indicated by the aforementionedvehicle position information as a reference position for the distance.

Next, inclination processor 122 determines the mode of inclination ofdisplay object 10 that points to the pointed direction as the navigationdirection, by controlling yaw angle ψ and roll angle φ of display object10 on the basis of the attribute of the determined path point.Specifically, inclination processor 122 controls yaw angle ψ on thebasis of the attribute of the path point and controls roll angle φ inaccordance with controlled yaw angle ψ.

In the determination of yaw angle ψ, inclination processor 122determines yaw angle ψ of display object 10 on the basis of theattribute of the path point as in the example illustrated in (a) or (b)in FIG. 9A. For example, the attribute of the path point may be thetangential direction at the path point on the path as illustrated in (a)in FIG. 9A. Note that inclination processor 122 determines thistangential direction as the aforementioned navigation direction. Thisnavigation direction may be a direction expressed using the northdirection as a reference. In the determination of the mode ofinclination of display object 10, inclination processor 122 controls yawangle ψ of display object 10 such that the pointed direction of displayobject 10 coincides with the tangential direction serving as thenavigation direction.

Alternatively, the attribute of the path point may be the position ofthe path point as illustrated in (b) in FIG. 9A. In the determination ofthe mode of inclination of display object 10, inclination processor 122controls yaw angle ψ of display object 10 such that the pointeddirection of display object 10 coincides with a direction from vehicle 2toward the path point. In this case, inclination processor 122determines the direction from vehicle 2 to the path point as thenavigation direction. This direction from vehicle 2 to the path point ishereinafter also referred to as a “path-point direction”.

FIG. 9B is a diagram showing one example of the method of determining apath point according to the present embodiment. Note that (a) in FIG. 9Bshows an example of determining a second point on the path as theposition of the path point, and (b) in FIG. 9B shows an example ofdetermining a first point on the path as the position of the path point.

For example, it is assumed, as illustrated in (a) in FIG. 9B, thatvehicle 2 is travelling on a gentle right curve in the road and thenapproaches a sharp left curve in the road along the path. In this case,path-point determiner 125 first determines a position corresponding tothe travelling speed of vehicle 2 on the path as the first point. Forexample, as the travelling speed of vehicle 2 becomes higher, path-pointdeterminer 125 determines, as the first point, a position on the paththat is away by a longer distance from vehicle 2 along the path, and asthe travelling speed of vehicle 2 becomes lower, path-point determiner125 determines, as the first point, a position on the path that is awayby a shorter distance from vehicle 2 along the path.

Here, if a path direction that is the tangential direction at the firstpoint on the path is used as the navigation direction, since the pathdirection is a leftward direction, yaw angle ψ of display object 10 iscontrolled such that the pointed direction of display object 10 isdirected to the left. However, in the case where vehicle 2 isapproaching a gentle right curve in the road, the display of suchdisplay object 10 pointing to the leftward direction may mislead user 1or cause user discomfort. Note that the aforementioned possibility ofmisleading the user or causing user discomfort lies not only in the casewhere the vehicle is travelling on a sharp curve such as a sharp leftcurve, but also in the case where the vehicle makes a right or left turnat a right/left turn point on the path. The right/left turn point is apoint of intersection that allows a right or left turn.

Thus, path-point determiner 125 according to the present embodimentidentifies a section including a sharp curve or a right/left turn pointon the path and also uses this section to determine the position of thepath point, instead of determining the position of the path pointthrough simple use of the travelling speed of vehicle 2. In such asection including a sharp curve or a section in which vehicle 2 makes aright or left turn at a right/left turn point, the rate of change in thepath direction is high. Therefore, path-point determiner 125 uses therate of change in the path direction and identifies a section in whichthe absolute value for the rate of change is greater than a thresholdvalue, as a variable section. Note that the rate of change in the pathdirection is the amount of change in the tangential direction on thepath per unit length of the path. The unit length may, for example, be100 m, and the amount of change in the tangential direction may be 45°.That is, the variable section is a section including a sharp curve or asection including a point of intersection for a right or left turn, andis also a section in which the tangential direction changes by 45° ormore within the range of 100 m along the path.

Specifically, path-point determiner 125 determines the first point onthe path depending on the travelling speed of vehicle 2. Then,path-point determiner 125 determines whether there is a variable sectionbetween the current location of vehicle 2 and the first point, thevariable section being a section in which the absolute value for therate of change in the path direction at each point on the path isgreater than a threshold value. In the case where it is determined thatthere is a variable section, path-point determiner 125 sets a secondpoint immediately before the variable section on the path. Then,path-point determiner 125 determines either the first point or thesecond point as the position of the path point depending on a differencebetween the path direction at the second point and the travel directionof vehicle 2.

For example, in the case where the difference between the path directionat the second point and the travel direction of vehicle 2 is out of apredetermined range as illustrated in (a) in FIG. 9B, path-pointdeterminer 125 determines the second point as the position of the pathpoint. This enables directing the pointed direction of display object 10to the right and appropriately guiding user 1 or vehicle 2 along a rightcurve.

On the other hand, in the case where vehicle 2 is travelling on theright curve in the road and approaching the second point, the traveldirection of vehicle 2 becomes closer to the path direction at thesecond point as illustrated in (b) in FIG. 9B. Thus, in the case wherethe difference between the path direction at the second point and thetravel direction of vehicle 2 is within the predetermined range,path-point determiner 125 determines the first point as the position ofthe path point. This enables directing the pointed direction of displayobject 10 to the left and appropriately guiding user 1 or vehicle 2along a sharp left curve. Or, it is possible to appropriately guide user1 or vehicle 2 in a left-turn direction at a right/left turn point. Notethat the aforementioned predetermined range may, for example, be 10°.

While FIG. 9B shows one example of the case in which a gentle curve, asharp curve opposite to the direction of the gentle curve, and a rightor left turn are sequential along the path, the present disclosure isalso applicable to other cases. For example, even if the path is curvedin only one direction, it is possible to direct the pointed direction ofdisplay object 10 to an appropriate direction and it is possible toavoid misleading user 1 or vehicle 2 and to alleviate user discomfort.Although the path direction in the example illustrated in FIG. 9B is thetangential direction on the path, the path direction may be thedirection from vehicle 2 toward the path point, i.e., the path-pointdirection.

In this way, path-point determiner 125 according to the presentembodiment controls the position of the path point depending on thetravelling speed of vehicle 2. Since this path point is used to presentthe navigation direction by display object 10, display object 10 iscapable of presenting an appropriate navigation direction responsive tothe travelling speed to user 1. Specifically, path-point determiner 125determines the first point on the path depending on the travelling speedof vehicle 2. Then, in the case where it is determined that there is avariable section between the current location of vehicle 2 and the firstpoint, the variable section being a section in which the absolute valuefor the rate of change in the path direction at each point on the pathis greater than the threshold value, and where the difference betweenthe travel direction of vehicle 2 and the path direction at the secondpoint located immediately before the variable section is out of thepredetermined range, path-point determiner 125 determines the secondpoint as the position of the path point. On the other hand, in the casewhere the above difference is within the predetermined range, path-pointdeterminer 125 determines the first point as the position of the pathpoint.

Therefore, in the case where there is a variable section, either one ofthe first and second points before and after the variable section thatdepends on the travel direction of vehicle 2 is determined as theposition of the path point. Accordingly, it is possible to reduce thepossibility that display object 10 points to an inappropriate navigationdirection relative to the travel direction of vehicle 2.

FIG. 10 is a diagram showing one example of controlling the roll angleof display object 10 according to the present embodiment. Note that (a)in FIG. 10 shows display object 10 when viewed from a yaw-axisdirection, (b) in FIG. 10 shows display object 10 when viewed from adirection perpendicular to the roll axis, and (c) in FIG. 10 showsdisplay object 10 when viewed from a roll-axis direction.

Inclination processor 122 of controller 120 determines yaw angle ψ ofdisplay object 10, for example as illustrated in (a) in FIG. 10 , i.e.,as illustrated in the example illustrate in FIG. 9A. Inclinationprocessor 122 determines roll angle φ in accordance with yaw angle ψ ofdisplay object 10 as illustrated in (b) and (c) in FIG. 10 .Specifically, as yaw angle ψ increases, inclination processor 122determines a larger role angle φ. For example, in the case where displayobject 10 rotates counterclockwise about the yaw axis as a central axis,yaw angle ψ increase. At this time, roll angle φ increases to causedisplay object 10 to be inclined in the vertical direction asillustrated in (b) in FIG. 10 .

In this way, as illustrated in FIGS. 9A to 10 , inclination processor122 according to the present embodiment determines the mode ofinclination of display object 10 pointing to the pointed direction asthe navigation direction, by controlling yaw angle ψ and roll angle φ ofdisplay object 10 on the basis of the attribute of the path point. Thus,display object 10 can be displayed like a bird or plane view to leadvehicle 2 to the destination. Accordingly, display object 10 can beformed not into a long carpet-like shape but into a short shape pointingto one direction such as an arrowhead. As a result, it is possiblereduce the occurrence of overlay misregistration or loss of displayobject 10 and alleviate discomfort felt by user 1 due to the overlaymisregistration or loss of display object 10 while appropriatelynotifying user 1 of the navigation direction by the one directionpointed to by display object 10. Moreover, since roll angle φ is alsocontrolled, even if display object 10 extends off the road when vehicle2 is travelling on a curve or the like in the road, it is possible toalleviate discomfort felt on the extension off of display object 10 byuser 1.

Inclination processor 122 also controls yaw angle ψ of display object 10such that the pointed direction coincides with the tangential directionas illustrated in (a) in FIG. 9A. Or, inclination processor 122 controlsyaw angle ψ of display object 10 such that the pointed directioncoincides with the direction from vehicle 2 toward the path point asillustrated in (b) in FIG. 9A. Accordingly, it is possible to notifyuser 1 of an appropriate navigation direction for directing vehicle 2 tothe path point by the pointed direction of display object 10.

[Position Control of Display Object]

FIG. 11 is a diagram showing one example of controlling the position ofdisplay object 10 according to the present embodiment. Note that (a) inFIG. 11 indicates the positional relationship between vehicle 2 anddisplay object 10 when viewed from above vehicle 2, and (b) in FIG. 11shows the position of display object 10 visually recognized in displayrange d1 of windshield 2 a.

First, position processor 121 of controller 120 identifies the positionof the path point determined by path-point determiner 125 on the basisof the notification from path-point determiner 125.

Then, position processor 121 of controller 120 determines a planeposition (x, y) of display object 10 as illustrated in (a) in FIG. 11 .The plane position (x, y) refers to the position of display object 10arranged in a plane. The plane may be a road surface on which vehicle 2is travelling, or may be a tangent plane to the road surface. Position yin plane position (x, y) indicates a position along a longitudinal axisthat is an axis along the travel direction of vehicle 2 that is one oftwo axes arranged along the above plane and orthogonal to each other.That is, position y is a depth position of visually recognized displayobject 10 in the travel direction of vehicle 2. Positon x in planeposition (x, y) indicates a position along a lateral axis that isorthogonal to the longitudinal axis and that is one of the two axesarranged along the above plane. That is, position x is a lateralposition of visually recognized display object 10 in the breadthdirection of vehicle 2. Hereinafter, the breadth direction is alsoreferred to as the lateral direction or the lateral axial direction.Note that position processor 121 may use the travel direction indicatedby the aforementioned vehicle azimuth information as the traveldirection of vehicle 2.

Specifically, position processor 121 controls position y depending onthe travelling speed of vehicle 2. For example, as the travelling speedof vehicle 2 becomes higher, position processor 121 determines positiony that is farther away from vehicle 2, and as the travelling speed ofvehicle 2 becomes lower, positon processor 121 determines position ythat is closer to vehicle 2. In the determination of position y,position processor 121 may determine position y nonlinearly relative tothe travelling speed, or may determine position y linearly relative tothe travelling speed.

As to position x, position processor 121 controls position x dependingon the direction from vehicle 2 to the path point. Specifically,position processor 121 identifies angle α between the travel directionof vehicle 2 and the path-point direction from vehicle 2 to the pathpoint. Then, position processor 121 calculates angle β that is 1/n timesof angle α and identifies a direction that forms angle β with the traveldirection of vehicle 2. Note that this direction forming angle β is adirection inclined from the travel direction toward to the path-pointdirection. Then, position processor 121 determines the lateral axialposition of a point located at position y from among points on astraight line along the direction forming angle β. Referring to theaforementioned 1/n times, n is a real number greater than one and may,for example, be three. Alternatively, position processor 121 maycalculate 1/n times of the distance in the lateral axial direction fromvehicle 2 to the path point and determine, as position x, a point thatis away by the aforementioned 1/n-fold distance to the path point fromvehicle 2 in the lateral axial direction. Moreover, position processor121 may determine angle β or position x linearly relative to the lateralaxial distance from angle α or vehicle 2 to the path point.

In the determination of the plane position (x, y) of display object 10,position processor 121 limits the plane position (x, y) of displayobject 10 such that display object 10 does not extend off display planerange d2 in the aforementioned plane. As illustrated in (b) in FIG. 11 ,display plane range d2 is the range corresponding to display range d1 ofwindshield 2 a. The length of display plane range d2 in the traveldirection corresponds to the length of display range d1 in the up-downdirection, and the length of display plane range d2 in the lateraldirection corresponds to the length of display range d1 in the lateraldirection. As a result, it can be said that position processor 121limits plane position (x, y) of display object 10 such that displayobject 10 does not extend off display range d1. That is, positionprocessor 121 limits position x of display object 10 such that displayobject 10 becomes visually recognizable within a predetermined range inthe breadth direction of vehicle 2. Position processor 121 also limitsposition y of display object 10 such that display object 10 becomesvisually recognizable within a predetermined range in the up-downdirection of vehicle 2.

In this way, position processor 121 according to the present embodimentcontrols the lateral position, i.e., position x, of display object 10depending on the direction from vehicle 2 to the path point.Accordingly, it is possible to reduce the possibility that displayobject 10 sticks to a boundary at the lateral edge of display range d1or suddenly moves off the boundary as a result of controlling n in theaforementioned 1/n times. Note that the situation in which displayobject 10 sticks to the boundary refers to a situation in which displayobject 10 does not depart from the boundary for a certain period of timewhile vehicle 2 is travelling.

Position processor 121 also limits the lateral position of displayobject 10 such that display object 10 becomes visually recognizablewithin display range d1. This reduces the possibility that the left orright portion of display object 10 becomes lost or that display object10 becomes invisible.

Position processor 121 also controls the depth position, i.e., positiony, of display object 10 depending on the travelling speed of vehicle 2.For example, as the travelling speed of vehicle 2 becomes lower, aposition closer to vehicle 2 is determined as the depth position. Thisreduces the possibility that, when vehicle 2 is travelling slowly on arelatively congested road, display object 10 is overlaid on a vehicletravelling ahead.

Position processor 121 also limits the depth position of display object10 such that display object 10 becomes visually recognizable withindisplay range d1. This reduces the possibility that the upper or lowerportion of display object 10 becomes lost or that display object 10becomes invisible.

[Shape or Pitch Angle Control of Display Object]

FIG. 12 is a diagram showing one example of controlling the shape ofdisplay object 10 according to the present embodiment.

As illustrated in (a) to (c) in FIG. 12 , shape processor 124 ofcontroller 120 changes the shape of display object 10 depending on yawangle ψ. For example, shape processor 124 changes overall length L ofdisplay object 10. For example, in the case where yaw angle ψ is 0° asillustrated in (a) in FIG. 12 , shape processor 124 sets overall lengthL to L1, and in the case where yaw angle ψ is 45° as illustrated in (b)in FIG. 12 , shape processor 124 sets overall length L to L2 (L2<L1). Inthe case where yaw angle ψ is 90°, shape processor 124 sets overalllength L to L3 (L3<L2). This change in overall length L changes theratio between overall length L and the width and consequently changesthe shape of display object 10.

For example, in the case where display object 10 is at far position y,user 1 visually recognizes display object 10 in a direction closer tothe horizontal direction. Thus, if the shape of display object 10 is notchanged in such a case, display object 10 visually recognized by user 1in display range d1 has a short width in the up-down direction. That is,display object 10 looks like collapsed in the longitudinal direction. Asa result, user 1 has difficulty in grasping the pointed direction ofdisplay object 10.

In view of this, shape processor 124 according to the present embodimentincreases overall length L of display object 10 as yaw angle ψapproaches 0° as illustrated in FIG. 12 . This shortens the width in theup-down direction of display object 10 visually recognized by user 1even if display object 10 is at far position y. Thus, it is possible toreduce the possibility that display object 10 looks like collapsed.

Alternatively, inclination processor 122 of controller 120 may controlpitch angle θ of display object 10 to reduce the possibility thatdisplay object 10 looks like collapsed. That is, in the determination ofthe mode of inclination of display object 10, inclination processor 122further controls pitch angle θ of display object 10 depending on yawangle ψ of display object 10. For example, inclination processor 122increases pitch angle θ of display object 10 as yaw angle ψ of displayobject 10 approaches 0°. That is, pitch angle θ is controlled such thatthe pointed direction of display object 10 becomes closer to thevertical direction.

Although, in the aforementioned example, controller 120 controls theshape or pitch angle θ of display object 10 depending on yaw angle ψ,the shape or pitch angle θ of display object 10 may also be controllednot only depending on yaw angle ψ but also depending on position y. Forexample, in the case where the distance from vehicle 2 to position y isgreater than or equal to a threshold value, controller 120 may controlthe shape or pitch angle θ of display object 10 depending on yaw angleψ.

In this way, controller 120 according to the present embodiment controlsthe shape or pitch angle θ of display object 10 depending on yaw angle ψof display object 10. This improves visibility of display object 10 evenif the depth position, i.e., position y, of display object 10 is farfrom vehicle 2.

[Design Control of Display Object]

FIG. 13 is a diagram showing one example of controlling the design ofdisplay object 10 according to the present embodiment.

For example, as illustrated in (a) in FIG. 13 , vehicle 2 may travel ona road curved to the left along the path indicated by the pathinformation and then make a right turn at a right/left turn point. Inthis case, design processor 123 of controller 120 controls the design ofdisplay object 10 depending on the distance from the current location ofvehicle 2 to the right/left turn point that is located forward of thepath point on the path. For example, design processor 123 measures thedistance along path from the current location of vehicle 2 indicated bythe vehicle position information to the right/left turn point indicatedby the path information. Then, if the path information indicates to makea right turn at the right/left turn point when the distance to theright/left turn point becomes less than or equal to the threshold value,design processor 123 changes the color or brightness of the right halfof display object 10. As one specific example, design processor 123 maychange the color of the right half of display object 10, the overallcolor of which is green, to yellow. Alternatively, design processor 123may change the color of part of the right half of display object 10,i.e., the color of the right end, to yellow. As another alternative,design processor 123 may display another object 10 a indicating a rightturn around display object 10 as illustrated in (b) in FIG. 13 , or maycause object 10 a to blink on and off. Note that object 10 a indicates aright or left turn from the relative positional relation between displayobject 10 and object 10 a. The threshold value for the distance to theright/left turn point may, for example, be 300 m.

Accordingly, it is possible to indicate the navigation direction forguiding vehicle 2 to the left curve by controlling yaw angle ψ ofdisplay object 10 to direct the pointed direction of display object 10to the left, and it is also possible to appropriately notify user 1 ofthe presence of a right turn following the left curve by changing thedesign of display object 10.

Alternatively, design processor 123 may control the design of displayobject 10 depending on an expected arrival time from the currentlocation of vehicle 2 to the right/left turn point that is locatedforward of the path point on the path. For example, design processor 123may measure the distance along the path from the current location ofvehicle 2 indicated by the vehicle position information and theright/left turn point indicated by the path information and calculatethe expected arrival time by dividing the measured distance by thetravelling speed of vehicle 2 indicated by the vehicle speedinformation. Then, if the path information indicates to make a rightturn at the right/left turn point when the expected arrival time up tothe right/left turn point becomes less than or equal to a thresholdvalue, design processor 123 changes the color or brightness of the righthalf of display object 10. Although, in the example illustrated in FIG.13 , the left curve is followed by the right turn, the directions of thecurve and the turn may be reversed. A case is also possible in which aright or left turn is followed by a curve, or two curves are sequential,or a right turn and a left turn are sequential. The threshold value forthe expected arrival time may, for example, be in the range of 10seconds to one minute.

In this way, it is possible, according to the present embodiment, tonotify user 1 of the navigation direction to the right/left turn pointby the mode of inclination of display object 10 and to appropriatelynotify user 1 of a right or left turn at the right/left turn point bycontrolling the design of display object 10. That is, even if thenavigation direction to the right/left turn point is different from theright- or left-turn direction at the right/left turn point, it ispossible to appropriately notify user 1 of both of the navigationdirection and the right- or left-turn direction at the same time. Thatis, even if the pointed direction of display object 10 is directed tothe left in order to guide vehicle 2 along the road curved to the left,it is possible to appropriately notify user 1 of the need to make aright turn at the next right/left turn point.

FIG. 14 is a diagram showing another example of controlling the designof display object 10 according to the present embodiment.

For example, in the case where vehicle 2 is travelling on a road with aplurality of traffic lanes as illustrated in (a) in FIG. 14 , anothervehicle 3 is approaching vehicle 2. At this time, design processor 123notifies user 1 of the approach of other vehicle 3 by controlling thecolor of display object 10.

Specifically, input unit 110 of display device 100 acquires sensinginformation indicating the approach of other vehicle 3 from sensor 23that detects the approach of other vehicle 3 to vehicle 2. Note that thefunction of acquiring such sensing information is part of the functionof input unit 110, and it can also be said that input unit 110 includesa second input unit that achieves this function.

Design processor 123 of controller 120 controls the design of displayobject 10 in accordance with the sensing information acquired by inputunit 110. For example, the sensing information indicates that othervehicle 3 is approaching from the right side of vehicle 2. In this case,design processor 123 changes the color or brightness of the right end ofdisplay object 10. As one specific example, design processor 123 maychange the color of this right end from green to red. Alternatively,design processor 123 may cause this right end to blink on and off inred. As another alternative, design processor 123 may cause the color ofthe entire or part of the right half of display object 10 other than theright end of display object 10 to change or blink on and off. As yetanother alternative, design processor 123 may display object 10 a forattracting attention of user 1 around display object 10 as illustratedin (b) in FIG. 14 , or may cause object 10 a to blink on and off.

In this way, it is possible, according to the present embodiment, toattract attention of user 1 to the approach of other vehicle 3 bycontrolling the design of display object 10. For example, it is possibleto attract attention of user 1 to the approach of other vehicle 3 incases such as where vehicle 2 changes the traffic lane or where vehicle2 enters a rendezvous point of the traffic lanes.

[Movement Control of Display Object]

FIG. 15 is a diagram showing one example of controlling the movement ofdisplay object 10 according to the present embodiment.

For example, vehicle 2 may travel along the path indicated by the pathinformation and make a left turn at a right/left turn point asillustrated in (a) in FIG. 15 . In this case, position processor 121 ofcontroller 120 moves display object 10 in the navigation direction whenthe distance along the path from the current location of vehicle 2 tothe right/left turn point becomes less than or equal to a thresholdvalue. Note that moving display object 10 in the navigation directioncan also be said as moving display object 10 in the pointed direction.In the example illustrated in (a) in FIG. 15 , position processor 121moves display object 10 to the left.

Alternatively, position processor 121 may move display object 10 in thenavigation direction when the expected arrival time from the currentlocation of vehicle 2 to the right/left turn point on the path becomesless than or equal to a threshold value. For example, position processor121 may measure the distance along the path between the current locationof vehicle 2 indicated by the vehicle position information and theright/left turn point indicated by the path information and calculatethe expected arrival time by dividing the measured distance by thetravelling speed of vehicle 2 indicated by the vehicle speedinformation. Then, design processor 123 moves display object 10 in thenavigation direction when the expected arrival time to the right/leftturn point becomes less than or equal to the threshold value.

This enables user 1 to easily notice a right or left turn at theright/left turn point.

Alternatively, position processor 121 may repeatedly move display object10 in the navigation direction as illustrated in (b) in FIG. 15 ,instead of moving it only once. For example, position processor 121 mayreturn display object 10 to the original position after having moveddisplay object 10 in the navigation direction, and then move displayobject 10 again in the navigation direction.

In this way, it is possible, according to the present embodiment, byallow user 1 to easily notice the right/left turn point as well as tonotify user 1 of the timing of the right or left turn at the right/leftturn point by moving display object 10 in the navigation direction.

[Height or Design Control of Display Object]

FIG. 16 is a diagram showing one example of controlling the height ofdisplay object 10 according to the present embodiment.

Position processor 121 of controller 120 controls the height, i.e.,position z, of display object 10 depending on the reliability ofnavigation by navigation device 21.

For example, input unit 110 of display device 100 acquires reliabilityinformation indicating the reliability of navigation from navigationdevice 21. Note that the function of acquiring such reliabilityinformation is part of the function of input unit 110, and it can alsobe said that input unit 110 includes a first input unit that archivesthis function.

The reliability information is information generated by navigationdevice 21 and may be included in the aforementioned vehicle-relatedinformation. The reliability of navigation corresponds to the accuracyof the path set by navigation device 21 and the accuracy of the currentlocation of vehicle 2 and the travel direction thereof detected bynavigation device 21. For example, navigation device 21 may identify thereliability of navigation of vehicle 2 on the basis of, for example, theintensity of receiving GPS signals from a satellite and generatereliability information indicating the identified reliability. As onespecific example, in the case where the intensity of receiving GPSsignals is low, navigation device 21 may generate reliabilityinformation indicating low reliability, and in the case where theintensity of receiving GPS signals is high, navigation device 21 maygenerate reliability information indicating high reliability.Alternatively, navigation device 21 may identify the reliability ofnavigation depending on the type of a map used to navigate vehicle 2 andgenerate reliability information indicating the identified reliability.For example, in the case where a high-precision map is used innavigation, navigation device 21 may generate reliability informationindicating relatively high reliability, and in the case where anordinary map is used in navigation, navigation device 21 may generatereliability information indicating relatively low reliability. Note thatnavigation device 21 may switch the use of a high-precision map and anordinary map depending on the travelling point of vehicle 2, and forexample, may use the high-precision map when vehicle is travelling on ahighway.

Then, position processor 121 controls the height of visually recognizeddisplay object 10 from the road surface depending on the reliabilityinformation acquired by input unit 110. For example, as the reliabilityindicated by the reliability information becomes lower, positionprocessor 121 may determine higher position z as the height of displayobject 10, and as the reliability indicated by the reliabilityinformation becomes higher, position processor 121 may determine lowerposition z as the height of display object 10.

FIG. 17 is a diagram showing a more specific example of controlling theheight of display object 10 according to the present embodiment. Notethat (a) in FIG. 17 shows one example of display object 10 that has notundergone height control based on reliability, and (b) in FIG. 17 showsone example of display object 10 that has undergone height control basedon reliability.

For example, in the case where the reliability of navigation is low andthe height of display object 10 is not controlled depending on thereliability, display object 10 may be overlaid but deviates from theroad surface as illustrated in (a) in FIG. 17 . That is, overlaymisregistration may occur. Besides, the pointed direction of displayobject 10 may also deviate from the actual navigation direction.However, position processor 121 according to the present embodimentdisplays display object 10 at a high position as illustrated in (b) inFIG. 17 when the reliability of navigation is low. Display object 10that is displayed apparently at a high position above the road surfaceis hardly recognized as overlay misregistration by user 1. Besides, thedeviation in the pointed direction of display object 10 is also hardlyrecognized by user 1. Accordingly, it is possible to alleviatediscomfort felt by user 1 due to the overlay misregistration and thedeviation in the pointed direction.

Although, in the examples illustrated in FIGS. 16 and 17 , the height ofdisplay object 10 is controlled depending on the reliabilityinformation, i.e., depending on the reliability of navigation, othercontrol may be performed. For example, design processor 123 ofcontroller 120 may control the dynamic design of visually recognizeddisplay object 10 depending on the reliability information. For example,design processor 123 may cause display object 10 to blink on and offwhen the reliability indicated by the reliability information is lowerthan or equal to a threshold value. The blinking cycle may, for example,be 0.5 seconds. This creates a period of time during which displayobject 10 is not displayed. Thus, it is possible to alleviate userdiscomfort caused by overlay misregistration of display object 10. Notethat, in the case where the reliability is indicated by a numericalvalue from 0 to 1, the threshold value for the reliability may, forexample, be 0.5.

In this way, controller 120 according to the present embodiment controlseither the height of visually recognized display object 10 or thedynamic design of display object 10 depending on the reliabilityinformation. Accordingly, it is possible to alleviate discomfort felt byuser 1 due to overlay misregistration or a deviation in the pointeddirection of display object 10.

FIG. 18 is a diagram showing another example of controlling the heightof display object 10 according to the present embodiment.

As illustrated in FIG. 18 , position processor 121 of controller 120 maycontrol the height of visually recognized display object 10 from theroad surface depending on the distance along the path from the currentlocation of vehicle 2 to a right/left turn point on the path. Forexample, position processor 121 may lower the height of display object10, i.e., position z, when vehicle 2 approaches a right/left turn pointand the distance to the right/left turn point becomes shorter. Morespecifically, position processor 121 may lower the height of displayobject 10 as the distance from vehicle 2 to the right/left turn pointbecomes shorter, or may lower the height of display object 10 when thedistance becomes less than or equal to a threshold value.

In this way, the present embodiment allows user 1 to more easily noticea right or left turn at the right/left turn point. It is also possibleto prompt user 1 to slow down vehicle 2, i.e., it is possible to promptuser 1 to drive carefully.

[Offset Control of Display Object]

FIG. 19 is a diagram showing one example of controlling offsets of yawangle ψ and roll angle φ of display object 10 according to the presentembodiment.

In the case where navigation recommends traffic lane 32 different fromtraffic lane 31 on which vehicle 2 is travelling as a recommendedtraffic lane, inclination processor 122 of controller 120 appliesoffsets to yaw angle ψ and roll angle φ of display object 10. Note that(a) in FIG. 19 shows an example of not applying offsets to displayobject 10, and (b) in FIG. 19 shows an example of applying offsets todisplay object 10.

For example, in the case where the path information indicates to make aright or left turn at a right/left turn point that is located forward oftravelling vehicle 2 and the road on which vehicle 2 is travellingincludes multiple traffic lanes, navigation device 21 detects a trafficlane for the right or left turn as a recommended traffic lane. Forexample, in the case where the path information indicates to make aright turn, a right traffic lane is detected as a recommended trafficlane, and in the case where the path information indicates to make aleft turn, a left traffic lane is detected as a recommended trafficlane. Then, navigation device 21 outputs recommended-traffic-laneinformation indicating the recommended traffic lane. Input unit 110 ofdisplay device 100 acquires this recommended-traffic-lane information asthe vehicle-related information.

For example, in the case where input unit 110 does not acquire therecommended-traffic-lane information, inclination processor 122 does notapply offsets to display object 10 as illustrated in (a) in FIG. 19 .However, in the case where input unit 110 has acquired therecommended-traffic-lane information, inclination processor 122 appliesoffsets to display object 10 as illustrated in (b) in FIG. 19 . Forexample, the recommended-traffic-lane information may indicate trafficlane 32 as the recommended traffic lane. Thus, in the case whereinclination processor 122 has determined from the vehicle positioninformation that vehicle 2 is travelling on traffic lane 31 and hasdetermined that the recommended traffic lane is not traffic lane 31 buttraffic lane 32, inclination processor 122 applies, to display object10, offsets for directing the pointed direction to traffic lane 32. Asone specific example of applying offsets, inclination processor 122 mayadd an offset of ±2° to yaw angle ψ of display object 10 and add anoffset of the angle corresponding to the offset of ±2° to roll angle φof display object 10. As a result, in the example illustrated in FIG. 19, display object 10 is displayed inclined by 2° toward traffic lane 32.Note that inclination processor 122 may apply offsets to display object10, irrespective of whether or not the traffic lane on which vehicle 2is travelling is the recommended traffic lane. In this case, even if thetraffic lane on which vehicle 2 is travelling cannot be identified, itis possible to apply offsets to display object 10. The offset angle ofroll angle φ may or may not be equal to the offset angle of yaw angle ψ.

In this way, it is possible, according to the present embodiment, todirect the pointed direction of display object 10 to the recommendedtraffic lane by the application of offsets and to prompt user 1 totravel on the recommended traffic lane. Note that the offsets may befixed angles, or may be variable angles. For example, as the travellingspeed of vehicle 2 becomes higher, inclination processor 122 may applysmaller offsets, and as the travelling speed of vehicle 2 becomes lower,inclination processor 122 may larger offsets.

[Flowchart of Processing Operations]

FIG. 20 is a flowchart illustrating processing operations of displaydevice 100 according to the embodiment.

First, display device 100 acquires the vehicle-related information fromnavigation device 21, vehicle control device 22, and sensor 23 (stepS11). Then, display device 100 determines a path point from the pathindicated by the path information included in the vehicle-relatedinformation (step S12). Then, display device 100 determines the mode ofinclination of display object 10 by controlling yaw angle ψ and rollangle φ of display object 10 on the basis of, for example, the attributeof the path point (step S13). At this time, display device 100 maydetermine the mode of inclination by further controlling pitch angle θ.

Then, display device 100 determines the position (x, y, z) of displayobject 10 on the basis of the path point and the current location ofvehicle 2 (step S14), determines the design of display object 10 (stepS15), and further determines the shape of display object 10 (step S16).

Next, display device 100 applies video image light representing displayobject 10 in the mode of inclination determined in step S13 and havingthe position, design, and shape determined in step S14 to S16, towardwindshield 2 (step S17). As a result, user 1 visually recognizes displayobject 10 through windshield 2 a.

Here, display device 100 determines whether to end display of displayobject 10 (step S18). For example, in cases such as where vehicle 2 isparked, where the engine of vehicle 2 is stopped, or where displaydevice 100 has received an instruction to stop display, display device100 determines to end the display of display object 10 (Yes in stepS18). Otherwise, display device 100 determines not to end the display ofdisplay object 10 (No in step S18) and repeatedly executes theprocessing from step S11. In the case where the processing in step S11is repeated, the latest vehicle-related information is acquired at thistime. Thus, it is possible to update the mode of inclination, position,design, and shape of display object 10 at any time in accordance withthe latest vehicle-related information.

Other Embodiments

While the display device according to one or more aspects of the presentdisclosure has been described based on the embodiment, the presentdisclosure is not intended to be limited to this embodiment. The presentdisclosure may also include other variations obtained by making variousmodifications conceivable by those skilled in the art to the embodiment,without departing from the scope of the present disclosure.

For example, although controller 120 according to the embodimentdescribed above includes position processor 121, inclination processor122, design processor 123, and shape processor 124, controller 120 maynot include each of these processing units other than inclinationprocessor 122. Although inclination processor 122 controls yaw angle ψ,roll angle φ, and pitch angle θ of display object 10, pitch angle θ maybe fixed.

In the above-described embodiment, each constituent element may beconfigured as dedicated hardware, or may be realized by executing asoftware program suitable for each constituent element. Each constituentelement may also be realized by a program execution unit such as acentral processing unit (CPU) or a processor reading out and executing asoftware program recorded on a hard disk or a recording medium such as asemiconductor memory. Here, the software program for realizing displaydevice 100 or the like according to the above-described embodiment maycause a computer to execute each step included in, for example, theflowchart illustrated in FIG. 20 .

Note that the present disclosure also includes the following cases.

(1) At least one of the devices described above is specifically acomputer system configured by, for example, a microprocessor, a readonly memory (ROM), a random access memory (RAM), a hard disk unit, adisplay unit, a keyboard, and a mouse. The RAM or the hard disk unitstores computer programs. At least one of the devices described aboveachieves its function as a result of the microprocessor operating inaccordance with the computer programs. Here, the computer programs areconfigured by combining a plurality of instruction codes indicatingcommands to the computer in order to achieve predetermined functions.

(2) Some or all of the constituent elements that configure at least oneof the devices described above may be configured with one system LSI(large scale integration). The system LSI is a super-multi-function LSImanufactured by integrating a plurality of structural units on a singlechip, and is specifically a computer system configured to include amicroprocessor, a ROM, a RAM, and so on. The RAM stores computerprograms. The system LSI achieves its function as a result of themicroprocessor operating in accordance with the computer programs.

(3) Some or all of the constituent elements that configure at least onethe devices described above may be configured as an IC card detachablefrom the device or as a stand-alone module. The IC card or the module isa computer system configured by a microprocessor, a ROM, a RAM, and soon. The IC card or the module may include the aforementionedsuper-multi-function LSI. The IC card or the module achieves itsfunction as a result of the microprocessor operating in accordance withthe computer programs. The IC card or the module may also betamper-resistant.

(4) The present disclosure may be realized as the method describedabove. The present disclosure may also be realized as a computer programfor causing a computer to execute the method, or as digital signalsconsisting of computer programs.

The present disclosure may also be realized as a computer-readablerecording medium having computer programs or digital signals recordedthereon, examples of which include a flexible disc, a hard disk, aCompact Disc (CD)-ROM, a DVD, a DVD-ROM, a DVD-RAM, a Blu-ray(registered trademark) Disc (BD), and a semiconductor memory. As anotheralternative, the present disclosure may also be realized as digitalsignals recorded on such a recording medium.

The present disclosure may also be realized by computer programs ordigital signals transmitted via, for example, a telecommunication line,a wireless or wired communication line, a network represented by theInternet, or data broadcasting.

The present disclosure may also be realized by another independentcomputer system by transmitting programs or digital signals recorded ona recording medium or by transmitting programs or digital signals via,for example, a network.

Further Information about Technical Background to this Application

The disclosures of the following patent applications includingspecification, drawings, and claims are incorporated herein by referencein their entirety: Japanese Patent Application No. 2020-146228 filed onAug. 31, 2020, and PCT International Application No. PCT/JP2021/031521filed on Aug. 27, 2021.

INDUSTRIAL APPLICABILITY

The display device according to the present disclosure achieves theeffect of alleviating user discomfort on display objects and may beapplicable to, for example, a vehicle-mounted head-up display.

1. A display device comprising: a control circuit that determines a modeof inclination of a display object that is an image shaped to point toone direction; and a projector that projects light representing thedisplay object in the mode of inclination determined by the controlcircuit onto a display medium provided in a vehicle, to cause the lightto be reflected off the display medium toward a user in the vehicle toenable the user to visually recognize the display object in the mode ofinclination as a virtual image through the display medium, wherein thecontrol circuit determines the mode of inclination of the display objectthat points to the one direction as a navigation direction, bycontrolling a yaw angle and a roll angle of the display object inaccordance with an attribute of a path point that is set on a path fornavigation of the vehicle to a destination.
 2. The display deviceaccording to claim 1, wherein the control circuit further controls alateral position of the display object visually recognized in accordancewith a direction from the vehicle to the path point, the lateralposition being a position in a breadth direction of the vehicle.
 3. Thedisplay device according to claim 2, wherein the control circuitcontrols the lateral position of the display object to allow the displayobject to be visually recognized within a predetermined range in thebreadth direction of the vehicle.
 4. The display device according toclaim 1, wherein the control circuit further controls a position of thepath point in accordance with a travelling speed of the vehicle.
 5. Thedisplay device according to claim 4, wherein, when controlling theposition of the path point, the control circuit: determines a firstpoint on the path depending on the travelling speed of the vehicle; whenthere is a variable section between a current location of the vehicleand the first point and when a difference between a travel direction ofthe vehicle and a path direction at a second point located immediatelybefore the variable section is outside a predetermined range, thevariable section being a section in which an absolute value for a rateof change in the path direction at each point on the path is greaterthan a threshold value, determines the second point as the position ofthe path point; and when the difference falls within the predeterminedrange, determines the first point as the position of the path point. 6.The display device according to claim 1, wherein the control circuitfurther controls a depth position of the display object visuallyrecognized in accordance with a travelling speed of the vehicle, thedepth position being a position in a travel direction of the vehicle. 7.The display device according to claim 6, wherein the control circuitlimits the depth position of the display object to allow the displayobject to be visually recognized within a predetermined range in anup-down direction of the vehicle.
 8. The display device according toclaim 1, further comprising: a first input unit that acquiresreliability information indicating reliability of the navigation,wherein the control circuit controls either a height of the displayobject visually recognized from a road surface or a dynamic design ofthe display object in accordance with the reliability informationacquired by the first input unit.
 9. The display device according toclaim 1, wherein the control circuit further controls a height of thedisplay object visually recognized from a road surface in accordancewith a distance from a current location of the vehicle to a right/leftturn point on the path.
 10. The display device according to claim 1,wherein the attribute of the path point is a tangential direction at thepath point on the path, and when determining the mode of inclination ofthe display object, the control circuit controls the yaw angle of thedisplay object to cause the one direction to coincide with thetangential direction.
 11. The display device according to claim 1,wherein the attribute of the path point is a position of the path point,and when determining the mode of inclination of the display object, thecontrol circuit controls the yaw angle of the display object to causethe one direction coincide with a direction from the vehicle to the pathpoint.
 12. The display device according to claim 1, wherein the controlcircuit further applies an offset to the yaw angle and the roll angle ofthe display object when a traffic lane different from a driving lane ofthe vehicle is recommended as a recommended traffic lane in thenavigation.
 13. The display device according to claim 1, wherein thecontrol circuit further changes a shape of the display object inaccordance with the yaw angle of the display object.
 14. The displaydevice according to claim 1, wherein, when determining the mode ofinclination of the display object, the control circuit further controlsa pitch angle of the display object in accordance with the yaw angle ofthe display object.
 15. The display device according to claim 1, whereinthe control circuit further controls a design of the display object inaccordance with a distance from a current location of the vehicle to aright/let turn point located ahead of the path point on the path. 16.The display device according to claim 1, wherein the control circuitfurther controls a design of the display object in accordance with anexpected arrival time from a current location of the vehicle to aright/left turn point located ahead of the path point on the path. 17.The display device according to claim 1, wherein the control circuitfurther moves the display object in the navigation direction when adistance from a current location of the vehicle to a right/left turnpoint on the path is less than or equal to a threshold value.
 18. Thedisplay device according to claim 1, wherein the control circuit furthermoves the display object in the navigation direction when an expectedarrival time from a current location of the vehicle to a right/left turnpoint on the path is less than or equal to a threshold value.
 19. Thedisplay device according to claim 1, further comprising: a second inputunit that acquires sensing information indicating an approach of another vehicle from a sensor that detects the approach of the othervehicle to the vehicle, wherein the control circuit further controls adesign of the display object in accordance with the sensing informationacquired by the second input unit.